Hello GVGC subscribers and readers. I would first like to start off by saying how wonderful it is for my wife and I to have the opportunity to contribute to this blog and help with the many new and exciting things happening with GVGC.
As a brief introduction, my name is Eric Sellers, and my wife’s name is Kelsi. We have both been horticulture students at Clackamas Community College for 2 years, have both satisfied the requirements for the Associates of Applied Sciences Degree in horticulture, and have started our third year pursuing a Certificate of Urban Agriculture. Coincidentally, this is the program where we met Bob and began discussing our involvement with GVGC.
Now that the introductions are over, I can explain the reason for the long winded introduction. Bob has asked my wife and I to contribute articles and stories for this blog to better enlighten you, the readers, on what GVGC is doing, as well as some helpful information we have learned along the way through our Horticultural careers and education.
As my first order of business here, I would like to talk about seed genetics, and why most plants do not come true from seed. Bob specifically asked me to do a piece on this subject, because it is often hard to understand why it is things don’t come true to type from seed. Any simple search on Google will give you results from scholarly articles or complicated explanations on the subject, that are honestly more complicated than they should be. Basically, I am here to provide layman’s terms and explanations for somewhat complex ideas.
So first off, everyone knows the basics of genetics. They define how people look, the color of their hair, the color of their eyes, how tall they get, and so on. This is because of a person’s parents’ genetics matching up and creating a new set of genes. Since these new genes are based on the parent’s genetics, often-times the offspring will look similar to both parents. This is also true in that of plants.
People have been breeding plants for as long as farming has been around. This is because with the right amount of forethought, planning, and observation, you could make the perfect plant for your area.
Onto why it is a seed will often not come true to type. The example Bob keeps mentioning, as well as many other people, is apples. Apples, like many in the rosaceae family (the rose family) are easily cross pollinated. That is, in the words of Linda Beutler (a part time instructor at CCC as well as the curator at the Rogerson Clematis Collection), “they are very promiscuous.” That is to say, they breed readily, often whether you want them to or not.
Much like your parents came together to make your genes, they could have easily gone on to make someone else’s genes that is totally different from you. Whether from the same parents, or different parents. For this, many people use the punnett square to show the relationship of the genetics, and how they can differ, even within the offspring of the same parents. As your parents pass on their genes to you, you are then created with a series of genetics of dominant and recessive traits. It is from these that you get your physical appearance.
Punnette Square (click to view)
It is the same for an apple. Especially so even. The punnett square above shows the relationships of two similar genes, the “A” being the dominant and the “a” being recessive. Both parents are made up of “Aa”, but when crossed there’s a 25% chance that the offspring could be either “AA” or “aa”. While there might be a 50% chance the offspring will be the same in the example of the punnett square. Imagine now that there are thousands of more series of letters and number annotating different dominate and recessive traits. The chances of the offspring being the same as two similar parents no longer seems so likely.
One might then ask, “why not just breed the same plants together?” While that has been done with many plant species over the years to obtain highly productive plants, the problem with doing this practice on apples is that the same plant of the same genetics cannot pollinate itself. That is why you need at least one other apple variety within a mile of the producing apple trees, otherwise they will not fruit. If you don’t get any fruit, you won’t have any seeds.
In further layman’s terms, you need two parents of different genetics to get an apple with viable seeds. Because these parents have different genetics, the offspring will bear different traits. So in the end, an apple will not come true from seed, and often will not produce a tree that will produce an edible fruit at all.
This isn’t to say of course that growing seeds on from apples is a bad thing. To get new varieties, plant breeders have had to grow apple seedlings, and select the ones with desired qualities, and further breed subsequent generations to strengthen those traits. Breeding takes many generations for plant breeding programs to attain a good quality apple tree, because it takes 3-5 years to get the first fruit crop on an apple seedling. This makes it especially difficult to breed good apple trees, and thus isn’t usually a hobby taken on by home gardeners.
If you have any questions, feel free to post a comment, and I can answer them to the best of my knowledge. I hope this short article has helped with understanding some things about seed saving. I look forward to any comments, constructive criticism, and perhaps even doing a piece on saving seeds from other kinds of plants.